8.2 Musculature of the Vertebral Column and Intrinsic Trunk Flashcards
Extrinsic vs intrinsic back muscles
Extrinsic: originate in back, but insert into external site
Intrinsic: originate in back, and stay within back
What are the names of the deep and superficial layers of the intrinsic back muscles?
Deep: transversospinales
Superficial: erector spinae
What are the names of each of the transversospinales muscles? How many vertebrae do they cross?
Rotatores: 1-2
Multifidis: 3-4
Semispinalis: 6-10
Contraction of the transversospinal muscles causes ___lateral rotation
Contralateral (pyramid arrangement of muscles)
What are the segmental names given to muscles in the head, neck, thorax, and lumbar region?
Head: capitis
Neck: cervicis
Thorax: thoracis
Lumbar: lumborum
What is the anterior rectus sheath? What is it’s function?
- It is an aponeurosis
- Functions to synergize compressive forces of muscle
- Protects muscles, nerves, and blood vessels
What are the functions of the internal/external obliques?
Both: bilateral flexion and increased intra-abdominal pressure
Unilateral contraction: ipsilateral lateral flexion and rotation (ext: contra, int: ipsi)
In which structure do all oblique muscles insert?
Rectus sheath
At what level does the posterior rectus sheath stop? What is this line called? What happens inferior to this?
- Stops at level of umbilicus
- Known as arcuate (bow-shaped) line
- Below this, all aponeuroses merge anteriorly
The superficial fascia lies beneath the skin in the abdomen. What are the two components of this, and how does their structure differ?
Superficially, we have camper’s fascia (which is fat)
Deeper, we have Scarpa’s fascia, which is membranous connective tissue.
What kind of fascia sits between the three muscular layers of the abdominal wall?
Investing fascia; smaller than the muscle, but supporting.
Describe the three layers of the abdominal wall deep to the transversus abdominus?
- Transversalis fascia
- Extraperitoneal fat
- Parietal peritoneum
Imagine the anatomical course of the psoas major muscle. From which transverse processes does it originate, where does it insert, and what is its function?
- Originates from transverse processes of L1-L5
- Inserts into lesser trochanter of femur
- Causes hip flexion
Which muscles lies lateral to psoas major? Describe its anatomical course, and function.
- Iliacus muscle
- Originates in iliac crest
- Inserts on lesser trochanter
- Hip flexion
Describe the anatomical course and function of quadratus lumborum
- Originates on iliac crest
- Inserts into L1-L3 and twelfth rib
- Laterally flexes and extends the trunk
Which arteries supply the upper abdominal wall?
- Superior epigastric
- Musculophrenic artery
Which artery supplies the mid portion of the abdominal wall (along the S-I axis)?
Subcostal.
Which arteries supply the inferior abdominal wall?
- Inferior epigastric
- Deep circumflex iliac artery
Which arteries supply the subcutaneous tissue of the abdominal wall?
- Superficial epigastric
- Superficial circumflex iliac
Describe the blood supply to the posterior abdominal wall
Arteries/veins:
- Inferior phrenic
- 1st/2nd/3rd/4th lumbar vessels
Describe the innervation of the anteriolateral abdominal wall that arises from the thoracic nerves
Ventral rami of 7-11th intercostal nerves. Subcostal nerves below T12.
Which nerve supplies quadratus lumborum?
Subcostal (makes sense; this inserts directly below the twelfth rib)
Which nerve innervates iliopsoas?
Femoral nerve
The majority of the posterior abdominal wall is innervated by…
The dorsal rami of segmental spinal nerves.
Which scalene muscles attach to which ribs?
Ant/medial: 1st rib
Posterior: 2nd ribv
In what two ways do accessory abdominal expiratory muscles help in forceful expiration?
- Pull down on bottom ribs
- Push diaphragm up due to increased intra-abdominal pressure
Describe the blood supply to the thorax.
Posteriorly: intercostal arteries from thoracic aorta
Anteriorly: anterior intercostal arteties from internal thoracic artery, which arise from subclavian
Superiorly: 1st and 2nd intercostal arteries arise directly from subclavian
How does the venous drainage of the thorax differ from the arterial supply?
- Posterior intercostal veins drain into azygos (right), accessory azygos (left superior), and hemiazygos (left inferior)
- All drains into azygos, and into SVC
- Anterior intercostal veins drain into internal thoracic vein, which drain into the brachiocephalic veins
Describe the motor and sensory functions of the ventral rami of thoracic spinal nerves
Motor: intercostal muscles, transversus thoracis, subcostal, serratus posterior
Sensory: anterolateral abdominal wall and pleura
Describe the motor and sensory functions of the dorsal rami of thoracic spinal nerves
Motor: intrinsic back muscles
Sensory: posterior thoracic wall skin
